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Sources/Internals.PersistentHistoryFetcher.swift

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+//
+//  Internals.PersistentHistoryFetcher.swift
+//  CoreStore
+//
+//  Copyright © 2020 John Rommel Estropia
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+//
+
+import CoreData
+import Foundation
+
+
+// MARK: - Internals
+
+extension Internals {
+
+    // MARK: - PersistentHistoryFetcher
+
+    internal struct PersistentHistoryFetcher {
+
+        // MARK: Internal
+
+        internal let context: NSManagedObjectContext
+        internal let token: NSPersistentHistoryToken?
+
+        internal init(
+            context: NSManagedObjectContext,
+            token: NSPersistentHistoryToken?
+        ) {
+
+            self.context = context
+            self.token = token
+        }
+
+        internal func fetch() throws -> [NSPersistentHistoryTransaction] {
+
+            let request = self.newFetchRequest()
+            let fetchResult = try self.context.execute(request) as! NSPersistentHistoryResult
+            return fetchResult.result as! [NSPersistentHistoryTransaction]
+        }
+        
+
+        // MARK: Private
+
+        private func newFetchRequest() -> NSPersistentHistoryChangeRequest {
+
+            let historyFetchRequest = NSPersistentHistoryChangeRequest.fetchHistory(
+                after: self.token
+            )
+            guard #available(iOS 13.0, tvOS 13.0, watchOS 6.0, macOS 10.15, *) else {
+
+                return historyFetchRequest
+            }
+            guard let transactionFetchRequest = NSPersistentHistoryTransaction.fetchRequest else {
+
+                return historyFetchRequest
+            }
+
+            let context = self.context
+            transactionFetchRequest.predicate = NSCompoundPredicate(
+                type: .and,
+                subpredicates: [
+                    context.transactionAuthor.map { author in
+                        NSPredicate(
+                            format: "%K != %@",
+                            #keyPath(NSPersistentHistoryTransaction.author),
+                            author
+                        )
+                    },
+                    context.name.map { contextName in
+                        NSPredicate(
+                            format: "%K != %@",
+                            #keyPath(NSPersistentHistoryTransaction.contextName),
+                            contextName
+                        )
+                    }
+                ]
+                .compactMap({ $0 })
+            )
+            historyFetchRequest.fetchRequest = transactionFetchRequest
+
+            return historyFetchRequest
+        }
+    }
+}